Magnetron sputtering

ABSTRACT

A magnetron sputtering apparatus has a controller for selectively releasing the spread of plasma on a substrate on a support. The controller can also contain the plasma when the substrate is to be coated with the target material. This enables cleaning of the target surface during intervals between deposition of target material onto a desired substrate, such as a wafer, and ensures that layers or flakes of back-scattered deposited target material do not build up on the target itself. A platen coil is located between the magnetron and the support to increase both uniformity and density of target material arriving nearly normal to the substrate surface.

BACKGROUND OF THE INVENTION

This invention relates to apparatus and methods for magnetronsputtering.

In U.S. Pat. No. 5,593,551 issued to Lai, the disclosure of which isincorporated herein by reference, there is described an apparatus andmethod for magnetron sputtering in which a first closed-loop magnetmeans is positioned adjacent to a dish-shaped sputter target backsurface for creating a closed-loop magnetic tunnel to the front surfaceof the sputter target, the magnet means being in the form of a pluralityof magnets surrounding a central axis of a dish-shaped sputter targetfor containing and guiding a plasma relative to a substrate. Theimprovement is a second closed-loop magnet means positioned around thesputter target perimeter and being comprised of a number of buckingmagnets, which may be permanent magnets or electro magnets, whichcollectively provide a fixed field around the sputter target to therebyreduce or inhibit the spreading of the discharge track of the plasmabeyond the edge of the target as the operating pressure of thesputtering system is reduced.

The second closed-loop magnet means solves the problem in that thevoltage at which a magnetron operates is primarily a function of theease of ionisation. It is, in turn, a function of the gas, its pressure,the applied voltage, the strength of the magnetic field and theionisation losses from the plasma. As pressure is dropped so operatingvoltages rise until practical limits are reached e.g. the power supplyor electrical connections to the target.

Extremely high voltages are undesirable as they cause the plasma to emithigher energy electromagnetic waves that are potentially dangerous.Therefore, work has concentrated upon reduction of losses from theplasma by e.g. operating the plasma in an enclosed area bounded by abucking arrangement, as in the '551 patent. This allows magnetronoperation at pressures of 0.1 mT to 1 mT. This low pressure operation isbeneficial as a means of improving step coverage.

However, the design of this system and method of sputtering has thedisadvantage that due to the confinement of the primary magnetic fieldby the secondary magnetic field, there is little or zero erosion of thetarget material around the periphery of the target. As a consequence,the periphery thereof can thereafter be contaminated by back scattereddeposits of eroded material, such as atoms or molecules. Thisre-deposited material generally does not adhere well to the otherwiseclean periphery of the target and can thereafter flake off tocontaminate the substrate to which a thin film of the material is beingapplied or is to be applied.

SUMMARY OF THE INVENTION

The present invention is derived from the realisation that by replacingthe permanent bucking arrangement of the prior art, which essentiallyprovides a fixed magnetic field normal to the erosion region, withcontrollable DC coils located adjacent but outside of the periphery ofthe target assembly, it is then possible to vary the magnetic field,through the use of suitable switching and control circuits, to mitigatethe foregoing disadvantages and to “clean” the whole of the targetsurface before a new thin film process is begun.

According to a first aspect of the invention there is provided amagnetron sputtering apparatus including:

-   -   a target;    -   a magnetron assembly for the target arranged to produce uniform        erosion of the target across its surface, and    -   a support for holding a substrate on to which a film of target        material is to be deposited from the target, characterised in        that the apparatus further includes:    -   a closed loop magnet assembly located around the sputter target        perimeter for magnetically containing or restricting a plasma        formed adjacent to the target surface to alter the erosion        pattern of the target, and    -   a control for selectively releasing the spread of the plasma        over substantially the entire surface of the target such that        the surface thereof may be eroded and selectively containing the        plasma within the periphery of the target.

Prior art magnetron devices have been developed to provide good uniformerosion of the target but embodiments of the present invention allowpreferential erosion during deposition whilst further allowing theapparatus to operate in the normal mode for cleaning. With thisarrangement, sputtering apparatus according to the invention enablescleaning of the target surface during intervals between deposition oftarget material onto a desired substrate, such as a wafer. This ensuresthat layers or flakes of back scattered deposited target material do notbuild up on the target itself to thereafter e.g. flake off andcontaminate the wafer.

According to a second aspect of the invention there is provided a methodof magnetron sputtering a target by using apparatus in accordance withthe first aspect of the invention, which method includes the steps ofselectively varying or eliminating the magnetic field provided by thecoils to allow thereby the plasma to erode the entire surface of thetarget material when a substrate material to be coated is not beingexposed to the sputtered particles, to thereby prevent build up ofunwanted layers or flakes of the target material around the peripherythereof.

According to another aspect, the invention provides a method of sputterdeposition on a substrate without collimation filter including, duringsputter deposition, restricting the plasma to a central area of a targetby means of a circumjacent coil, and

-   -   applying a magnetic containment field around a space located        above a support for a substrate to be sputtered.

According to a further aspect there is provided a method of controllinga magnetron sputtering assembly having a target having a sputtersurface, the magnet of the magnetron assembly being moveable withrespect to the target and having a plasma generator and a plasmacontainment arrangement including operating the plasma containmentarrangement in a first, cleaning, mode wherein the plasma extends acrosssubstantially the whole sputter surface and a second, deposition mode,when the plasma is contained within the periphery of the sputtersurface, and

-   -   applying a magnetic containment field around a space located        above the support for a substrate to be sputtered.

The inventors have noted that the ability to confine the plasma adjacenta restricted area of target, reduces the angular distribution of thesputter material and, particularly in long throw chambers, can removethe need for collimators even with high aspect ratio holes.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example only, withreference to the accompanying drawings in which:

FIG. 1 is a schematic view shown in part cross section of the inside ofa sputtering chamber incorporating the apparatus of the invention;

FIG. 2 is a schematic cross-sectional view showing a selected portion oftarget material of the apparatus of FIG. 1 partially eroded by plasmacontained by the second magnet means;

FIG. 3 is a view corresponding to that of FIG. 2 but in which the wholeof the surface of one side of the target material has been eroded;

FIG. 4 is a schematic view of an alternative set-up including a furthermagnetic assembly;

FIGS. 5( a) and (b) are electron migrographs of the centre and edgerespectively of a wafer treated in accordance with Experiment 1;

FIGS. 6( a) and (b) are corresponding micrographs for Experiment 2;

FIGS. 7( a) and (b) are corresponding micrographs for the first set-upin Experiment 3;

FIG. 8 is a plot of base coverage against gas pressure with the targetcoil on;

FIG. 9 is a similar plot to FIG. 8 with the target coil off; and

FIGS. 10 and 11 are further such plots for different bias conditions atthe centre and edge respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring firstly to FIG. 1, there is shown a rotatable magnetronassembly shown generally at 1 comprising a closed loop array of magnetswhich is used to generate a magnetic field in the volume between thefront surface 2 a of a target 2, which may typically be titanium and anupper surface 3 a of a substrate 3, typically a semi-conducting orinsulating wafer.

The target 2 and substrate 3 are each contained within a vacuum lowpressure vessel in the form of a chamber 4 through which a stream ofnoble gas such as argon may pass at low pressure via an inlet valve 5and an outlet valve 6 from a respective gas source reservoir 7 and avacuum pump 8, typically a cryogenic pump.

An access door 9 is shown schematically in a side wall of the chamber 4,in order to allow access to the interior of the chamber and inparticular for removing at regular intervals a substrate 3 onto which athin film of the material from the target 2 has condensed followingsputtering of the latter via ionic bombardment, in a conventionalmanner.

Continuously wound DC coils 10 surround the magnetron assembly 1 and lieessentially coplanar with the major plane of the target 2. As will beappreciated, the DC coils 10 can effectively act as a solenoid whenexcited by a DC current to thereby generate an additional magneticfield, shown in dotted outline, surrounding the magnetron assembly 1 tothereby, when so excited, constitute a bucking arrangement of inwardlyfacing identical poles.

A control 10 a is provided for selective varying the strength of themagnetic field produced by the coils 10 by selectively varying suitableswitching and associated software within the control 10, in contrast tothe essentially fixed field arrangement shown in the '551 patent. Thishas a significant advantage in that, prior to the introduction of asubstrate into the chamber 3, excitation of the DC coils 10 can bevaried to create a wider containment of the surrounding the plasma suchthat the whole of the lower surface 2 a of the target 2 may be sputteretched and thereby cleaned, whereafter the substrate 3 can be introducedinto the chamber, the door 9 closed and a smaller containment “bucket”used to contain the plasma by a suitable adjustment to the powersupplied to the DC coils 10.

The field intensity produced by the coils 10 may be varied or eliminatealtogether, by simply reducing the current thereto in the intervalbetween thin film deposition on a desired substrate 3. This may bedemonstrated with reference to FIGS. 2 and 3, with FIG. 2 showing theetching pattern of the target 2 when the DC coils 10 are maintained in astate to contain closely the plasma, e.g.

when they are producing their maximum magnetic field. It will be seenthat, an annular perimeter 2 b comprised of a layer of re-depositedtarget material in the form of flakes may therefore build up, as in theapparatus described with reference to the '551 patent.

In contrast, and as can be seen in FIG. 3, by varying the magnetic fieldgenerated by the DC coils 10 to allow for the whole of the surface 2 aof the target to become exposed to ionic bombardment, the whole of thesurface may therefore be cleaned.

Variation of the magnetic-field by-the DC coils 10 may also be achievedby reversing the current flow, thereby providing a reversed field.

The cleaning made possible by the present invention is preferablyperformed at a higher pressure, typically of 1 mT to 10 mT since thereare problems with operating the magnetron at low pressure, for thereasons set out in the preamble hereto.

An example of the advantage of the apparatus and method of the inventionis found where titanium and titanium nitride is required to be depositedon a substrate as a barrier layer. Economically, it is advantageous todeposit both the titanium and the titanium nitride in the same processchamber and a common practice is to deposit the titanium by sputteringin an inert ambient atmosphere, such as in argon, and for the titaniumnitride in a reactive ambient atmosphere, including nitrogen. Thistechnique requires the target to be cleaned after every titanium nitridedeposition in order to remove nitrogen contamination from the surface.Using the apparatus and method of the invention there is therefore avery convenient opportunity to clean, additionally, the edge of thetarget by reducing, removing or reversing the magnetic field generatedby the external DC coils 10. A typical sequence would consist of thesteps of:

-   -   (1) Depositing titanium at low pressure under a high magnetic        “bucking” field generated by the external DC coils 10.    -   (2) when depositing titanium nitride using a high magnetic field        again generated by the external DC coils 10, and    -   (3) after removing the substrate, or shielding it from further        deposition by use of a shutter, which may also act as a        collector for the sputter-cleaned target material, removing,        reducing or reversing the field created by the DC coils 10 to        thereafter clean the whole of the target surface.

It will, however, be understood that the same sequence described abovecan be used to deposit these or other metal/metal nitride combinationswithout departing from the spirit or scope of the invention.

The above results show that the ‘target’ coil improves base coverageresults and it has also been discovered that this can be improvedfurther by the addition of another coil as shown in FIG. 4. Thisadditional platen coil 11 is located between the target and the wafer,but below the ‘target’ coil.

Before discussing this arrangement in detail, it may be helpful toprovide some background explanation. Sputtering so-called ‘stepcoverage’ is better than thermal evaporation because of the higherenergy level of the arriving material and the possibility of large areasources close to the substrate giving rise to a wide angulardistribution of arriving target material. Heating the substrateincreases this further. Ideally a conformal surface covering is desired,but the holes present a problem as all material to coat the insides andbase must pass through their mouths.

For barrier deposition the only surfaces of interest are within theholes. Ideally none would arrive on the field (an impossibility). Forcontact barriers, as the contact is at the base of the hole, only thebase of the hole requires coating and as contact holes get smaller andaspect ratios increase ideally only the base would be coated, leaving alarger volume of the hole for the principal conductor material having alower resistance than the barrier material.

So techniques to increase the directionality of the sputtering areemployed which attempt to have sputtered material with a flight pathnormal to the substrate surface thus improving the probability ofmaterial deposition at the base of high aspect ratio contact holes.

Two principal techniques are employed: ionisation and collimation. Theseare not mutually exclusive and ionisation of the sputtered material hasbeen used in combination with ‘collimating filters’ (being high aspectratio holes through which sputtered material must pass before arrivingat the substrate) and collimation whereby the source to substratedistance is increased e.g. to about 250 mm or about 500 mm (c.f.approximately 25 mm for normal magnetron sputtering). This increaseddistance allows low angle sputtered material to be lost to the sidewalls, with only that material arriving approximate normal to thesubstrate surface to arrive thus increasing the proportion of materialdeposited at the bottom of holes (which are, in essence, collimationfilters themselves).

In the present invention, it could be said that collimation is beingachieved, without using an actual collimator, by controlling the sourceof the sputtered material. The ‘target’ coil confines the plasma andthus reduces the angular distribution of sputtered material. Onesurprising result from the experiments shown below is that opticalspectroscopy suggests that metal ionisation takes place and thus thisarrangement achieves much of that using ionising coils but without theionising coil. In any event base coverage using this system issignificantly affected by the bias voltage on the support.

A further set of experiments investigated the influence of additionalelectromagnetic coils on the hole base coverage of sputtered titaniumfilms in a ‘long throw’ magnetron sputter chamber arrangement with anapproximate 240 mm source to substrate spacing. ‘Long throw’ generallyindicates a source substrate separation of over about 200 mm.

The set up is indicated in FIG. 4. One set of coils (“target coils”) 10was positioned around the target and upper part of the sputter chamberas shown schematically in FIG. 1. The polarity of the coil current wasset to induce a magnetic field with the same direction as the outer poleof the magnetron (“stronger outer poles”). This allows the system tooperate at low working gas pressures by confining the plasma at the edgeof the target, lowering the plasma impedance.

Additionally, a second set of electromagnetic coils (“platen coils”) 11was positioned around the lower part of the sputter chamber, close tothe support 12. The two sets of coils were operated independently usingdifferent power supplies. Experiments were run with the coils energisedto present different magnetic poles into the sputtering chamber. Ingeneral significantly better base coverage was achieved when both thetarget and platen coil magnetic polarity was opposed to the outer poleof the target magnetron (in a ‘bucking’ configuration) as shown inexperiment 3. So, for the sake of clarity, if the magnetron presented aNorth pole to its outer periphery, then the coils were generallyenergised so as to present a North pole on their inner surface.Reversing the magnetic field of the platen coil(s) 11, see experiment 4,(such that they present an opposing magnetic field to the outer field ofthe magnetron) was found to improve symmetry of base coverage across thewafer; however base coverage thickness was reduced.

Cathode power, sputter gas pressure and deposition temperature were keptconstant, whilst the platen bias power and coil currents were varied.The film properties investigated are base coverage (at the center andedge of the wafer) and the asymmetry of the base coverage (across onwafer and within one contact hole).

1. Experimental Process Parameters:

Target Power: 30 kW Ar Gas flow: 100 sccm Pressure: 2.5 mTorr PlatenTemp.: 200° C. Size of contact hole: 2.5 μm, aspect ratio: 2.7:12. Results and Conclusions

Experiment 1. Target Coil Current = OA Platen Coil Current = OA Platenbias voltage = −105 V Sputtering efficiency = 77 Å kW⁻¹ min⁻¹ Basecoverage centre = 26% Base coverage edge, average = 25% Asymmetry ofbase coverage across 4% wafer (max − min)/(max + min) = Asymmetry ofbase coverage within one 4% contact (max − min)/(max + min) =

The base coverage achieved is shown in the electron micrographs shown inFIG. 5.

Experiment 2 Target Coil Current = 17 OA Platen Coil Current = OA Platenbias voltage = −105 V Sputtering efficiency = 45 Å kW⁻¹min⁻¹ Basecoverage centre = 63% Base coverage edge, average = 51% Asymmetry ofbase coverage across 19% wafer (max − min)/(max + min) = Asymmetry ofbase coverage within one 15% contact (max − min)/(max + min) =

The base coverage achieved is shown in the electron micrographs shown inFIG. 6.

Experiment 4 Reversed 3 Platen Mag field Target Coil Current = 17 OA 17OA Platen Coil Current = 4 OA 4 OA Platen bias voltage = −90 V −125 VSputtering efficiency Å kW⁻¹ min⁻¹ = 41 42 Base coverage centre = 70%45% Base coverage edge, average = 59% 48% Asymmetry of base coverageacross 11% 5% wafer (max − min)/(max + min) = Asymmetry of base coveragewithin one 5% 1% contact (max − min)/(max + min) =

The base coverage achieved in experiment 3 is shown in the electronmicrographs shown in FIG. 7.

The reversed magnetic field experiment 4, in which only the field in theplaten coils is reversed, is not entirely comparable. The system haspower control for substrate bias, yet sputtering is voltage not currentdriven.

Anything over 100V is likely to cause significant resputtering, perhapsresputtering material on the base of holes onto the sidewalls. (Nomicrographs for reverse magnetic field shown here).

Experiment 6 Reversed (d) 5 Platen Mag field Target Coil Current = OA OAPlaten Coil Current = 17 OA 17 OA Platen bias voltage = −110 V −160 VSputtering efficiency Å kW⁻¹ min⁻¹ = 93 82 Base coverage centre = 59%23% Base coverage edge, average = 43% 19% Asymmetry of base coverageacross 16% 5% wafer (max − min)/(max + min) = Asymmetry of base coveragewithin one 1% 12% contact (max − min)/(max + min) =

Again these experiments and in particular the reversed magnetic fieldexperiment is not entirely comparable. The system has power control forsubstrate bias, yet sputtering is voltage not current driven. Anythingover −100 V is likely to cause significant resputtering, perhapsresputtering material on the base of holes onto the sidewalls. Nomicrographs for this experiment shown here. Further experiments arerequired keeping bias to a =/<−100 v threshold.

When comparing FIG. 5 and FIG. 6, it is apparent that the addition of‘target coils’ improves the base coverage of the sputtered films at thecentre as well as at the edge of the wafer by more than 50%

A drawback, however is the 3 to 4-fold increase in asymmetry of the basecoverage, across the wafer as well as within a contact hole. Thisincrease in asymmetry can however be significantly reduced by additionof platen coils 11 (FIG. 4). These ‘platen’ coils 11 increase bothuniformity (reduced asymmetry) and density of target material arrivingnearly normal to the substrate surface (increased hole base coverage).Reversing the magnetic pole of the platen coil further increasessymmetry across the wafer but at a reduced base coverage.

It is also noted that sputtering efficiency falls when the ‘target’magnetic coils are used. This is a measure of the average materialthickness upon the wafer per target kilowatts of power per minute. Itmay be that confinement of target plasma (of comparable power) to asmaller area increases plasma density sufficiently to significantlyincrease ionisation of sputtered material, but at the cost of a reducedsputtering rate due to the reduction in target area erosion due toreduced area of target exposed to plasma. Thus less material is beingsputtered, but at a higher energy level.

As has been mentioned before it is believed that metal ionisation istaking place as a result of this new configuration. Whilst it appearsdesirable to ionise an amount of the sputter material, completeionisation will not usually be appropriate.

The evidence for this is as follows:

This improvement in base coverage is gas pressure insensitive. Seeattached FIGS. 8 and 9. Whilst turning the bias on at 1 millitorr has asimilar percentile improvement in both cases, it is felt that the factthat the bias ‘on’ improvement is pressure insensitive shows that thereis a significant degree of metal ionization. This is extremely unusualfor magnetrons that are generally considered to produce insignificantamount of metal ions, thus internal RF driven ionizing coils are usuallyrequired.

It would appear that by confining the plasma and applying high levels ofpower to the magnetron at the ‘right’ pressure regime, metal ionisationis caused in the absence of a separate ionizing source. The addition ofa further coil between the “target” coil and the substrate furtherimproves base coverage and symmetry of base coverage across a wafer.Whilst these have been identified as two discrete D.C. coil assembliesin this disclosure, they may be one assembly with varied windingdensities to provide a graded magnetic field strength between the targetarea and the substrate area of the chamber. The experiments appear toshow that metal ionization occurs at high magnetron power levels only.At lower magnetron power levels, base coverage is poorer, see FIGS. 10(center) and 11 (edge) These experiments were conducted with only thetarget coil energized. They show the influence on hole base coverage ofwafer bias plotted against pressure at two different target powerlevels, 30 kw and 8 kw. As can be seen, at 30 kws of target power,considered to be a ‘high’ power level wafer bias has a significanteffect, whereas at ‘low’ target power bias has either no significanteffect, the differences being considered to be within measurement error.

The magnetron target considered throughout these experiments is of 330mm diameter, a conventional size for 200 mm wafers and of conventionalmoving magnet design meaning that there is an erosion path adjacent themagnetic racetrack giving a non-uniform plasma density over the targetsurface.

1. A magnetron sputtering apparatus comprising: a target having a targetsurface at which the target is to be eroded; a vacuum chamber in whichthe target surface is exposed; a magnetron assembly for the target, themagnetron assembly including a magnet moveable relative to the target toproduce uniform erosion of the target across the target surface; asupport for holding a substrate onto which a film comprising materialfrom the target is to be deposited; a closed loop magnet assemblyincluding a coil whose loops are located outside the vacuum chamber andextend around the perimeter of the target, for magnetically containingor restricting a plasma adjacent to the target surface to alter thepattern of the erosion of the target produced by the magnetron assembly;and a control operatively connected to the magnet assembly andconfigured to control the magnet assembly to selectively cause theplasma to spread over substantially the entire target surface such thatsubstantially the entire target surface may be eroded and cause theplasma to be confined adjacent to the target surface within an areasmaller than that occupied by the plasma when the plasma is spread oversubstantially the entire target surface.
 2. Apparatus as claimed inclaim 1 further including a further magnetic assembly located tosurround a space above the support.
 3. Apparatus as claimed in claim 2wherein the further magnetic assembly generates a magnetic field oflower strength than the closed loop magnetic assembly.
 4. Apparatus asclaimed in claim 2 wherein the closed loop magnetic assembly and thefurther magnetic assembly are operatively connected to separatecontrols.
 5. Apparatus as claimed in claim 2 wherein one or both of theclosed loop magnetic assembly and the further magnetic assembly arearranged in a bucking configuration with respect to the magnetronassembly.
 6. Apparatus as claimed in claim 2 wherein the furthermagnetic assembly is a closed loop magnetic assembly including a coil ofloops disposed outside and extending around the vacuum chamber. 7.Apparatus as claimed in claim 1 wherein the control is configured toselect controlling the magnetic assembly to cause the plasma to spreadover substantially the entire target surface when a substrate on thesupport is shielded from the target or prior to a substrate being placedon the support and to select controlling the magnetic assembly to causethe plasma to be confined adjacent to the target surface within saidarea when a film is to be deposited on the substrate.
 8. Apparatus asclaimed in claim 1 wherein the closed loop magnetic assembly is composedof a coil, and a DC power supply connected to the coil.
 9. Apparatus asclaimed in claim 1 wherein the target is substantially dished shaped.10. Apparatus as claimed in claim 1 wherein the coil is circumjacent thetarget surface.
 11. Apparatus as claimed in claim 1 wherein the targethas a front at which the target surface is presented, and a back, themagnet of the magnetron assembly facing the back of the target.
 12. Amagnetron sputtering apparatus including: a target having a targetsurface at which the target is to be eroded; a magnetron assembly forthe target, the magnetron assembly including a magnet moveable relativeto the target to produce uniform erosion of the target across the targetsurface; a support for holding a substrate onto which a film comprisingmaterial from the target is to be deposited; a closed loop magnetassembly including a coil, for magnetically containing or restricting aplasma adjacent to the target surface to alter the pattern of theerosion of the target produced by the magnetron assembly, and whereinthe coil is circumjacent the target surface; and a control operativelyconnected to the magnet assembly and configured to control the magnetassembly to selectively cause the plasma to spread over substantiallythe entire target surface such that substantially the entire targetsurface may be eroded and cause the plasma to be confined adjacent tothe target surface within an area smaller than that occupied by theplasma when the plasma is spread over substantially the entire targetsurface.
 13. Apparatus as claimed in claim 12 wherein the target has afront at which the target surface is presented, and a back, the magnetof the magnetron assembly facing the back of the target.
 14. A method ofcontrolling a magnetron sputtering apparatus including a target having asputter surface, a vacuum chamber in which the sputter surface isexposed, a magnetron assembly including a magnet moveable with respectto the target, a support for a substrate to be coated using materialfrom the target, a plasma generator and a plasma containmentarrangement, said method comprising: operating the plasma containmentarrangement in a first, cleaning mode wherein the plasma extends acrosssubstantially the whole sputter surface and a second, deposition modewherein the plasma is confined adjacent the sputter surface to an areasmaller than that when the plasma containment arrangement is operatingin the first, cleaning mode, and creating a magnetic containment fieldin a region around a space located above the support.
 15. A method asclaimed in claim 14 wherein the operating of the plasma containmentarrangement and the creating of the magnetic containment field comprisesupplying DC power to a plurality of electro-magnets.
 16. A method asclaimed in claim 15 wherein the electro-magnets are arranged in abucking configuration with respect to the magnetron assembly.
 17. Amethod as claimed in claim 14 wherein the plasma containment arrangementis operated in the first mode prior to a deposition process performed bythe sputtering apparatus or in-between deposition steps of a depositionprocess during which steps a substrate is successively coated usingmaterial from the target, and the plasma containment arrangement isoperated in the second mode during the deposition process or during thedeposition steps.
 18. A method as claimed in claim 14 wherein theoperating of the plasma containment arrangement and the creating of themagnetic containment field comprise generating magnetic fields ofdifferent intensities by supplying power to a target coil and to aplaten coil, respectively, the target coil extending circumjacent thesputter surface of the target, and the platen coil lying entirely in aregion between the first coil and the plane of a surface of thesubstrate which faces the sputter surface of the target.
 19. A method ofsputter deposition on a substrate, the method comprising: carrying out asputter deposition process in which a substrate disposed on a support iscoated, wherein the sputter deposition process comprises generatingplasma, eroding a surface of the target using the plasma in the presenceof a magnetic field generated by a magnetron assembly, and directingmaterial eroded from the target onto the substrate without the use of acollimation filter; and during the sputter deposition process,restricting the plasma to a central area of the target by creating amagnetic field using a coil circumjacent a surface of the target, andcreating a magnetic containment field in a region around a space locatedabove the support.
 20. A method as claimed in claim 19 wherein thesputter deposition process is performed in a long throw chamber.
 21. Amethod as claimed in claim 19 wherein a bias is applied to thesubstrate.
 22. A method as claimed in claim 21 performed without the useof a means dedicated to ionize material eroded from the target.
 23. Amethod as claimed in claim 21 further comprising applying power to themagnetron constituted by the target and the magnetron assembly, andcontrolling the power, the magnetic field used to restrict the plasma tothe central area of the target, and the magnetic containment field to atleast partially ionize material eroded from the target during thesputtering process.
 24. A method as claimed in claim 19 furthercomprising a cleaning process wherein the plasma is allowed to spreadbeyond the central area of the target for cleaning the target, whendeposition is not taking place.
 25. A method as claimed in claim 19wherein the restricting of the plasma and the creating of the magneticcontainment field comprise supplying DC power to a plurality ofelectro-magnets.
 26. A method as claimed in claim 25 wherein theelectro-magnets arranged in a bucking configuration with respect to themagnetron assembly.
 27. A method as claimed in claim 19 whereinrestricting of the plasma and the creating of the magnetic containmentfield comprise generating magnetic fields of different intensities bysupplying power to a target coil and to a platen coil, respectively, thetarget coil extending circumjacent the surface of the target beingeroded, and the platen coil lying entirely in a region between the firstcoil and the plane of a surface of the substrate which faces the surfaceof the target.